Are fad diets safe?

Chris Smith put this question to diet expert Sian Porter...

Sian -  This really is the time of year; there’s hundreds of fad diets out there, particularly at the moment. Often there is a grain of truth or some science there but often it’s been extrapolated. It’s either been misinterpreted or it’s been bigged up beyond its means. If you take something like eating chillies, which will raise your metabolic rate, that’s something that we’ve observed in a lab and then you might have observed it in animals, but no human studies have been done or, if they have, they might just  have been done on small amounts of people.

Chris - Made sweat quite a lot when I have them.

Sian - But then the amount that you have to eat, you’re talking about 50 plus chillies, and nobody can physically do this.

Chris - I was find. Dan’s nodding, he obviously likes curry as well as ...

Dan - Chillie

Sian - And there are dangers because often many of them tell you to remove whole food groups which, in the short term, might not do you any harm but in the long term it’s going to. Thinking about things like starchy carbs, something like fibre which affect your gut health, they obviously can put your diet out of balance which means then you might be overeating certain things and undereating other. Calories can be too low so you can be and, especially if you’re having to work and perform then you might just not have enough energy. They can be socially isolating; they can be very expensive so absolutely wouldn’t recommend them. If something sounds too good to be true it probably is, and if somebody’s trying to sell you something - beware.

Chris - Dan; when you’re exercising do you find that the diets you end up having to consume to perform at your optimum on the track, are they actually healthy diets or not?

Dan - I think if you look at them in relation to a conventional diet then they look quite different. I think one of the things we see in sport is that the diet has to fit the energetics of the sport. So the recommendations for say a track cyclist will be a very different to the recommendations for a marathon runner or even an ultramarathon runner. I was horrified when I worked with ultramarathon runners because I had made the assumption that we understand anything about nutrition suddenly these guys, it was nothing to do with carbohydrates, it was all just to do with energy intake.  Cheeseburgers - it was whatever  they felt like they could consume. For track cycling, we view it as being a healthy diet and you’d try and make sure you’d got the vegetables and you’d got the right balance but, actually, we were very much about carbohydrate and protein.